Spectroscopic studies of collodial ZnS

Abstract: This thesis is a summary and discussion of four papers, mainly dealing with reactions at the ZnS/water interface. The main analysis method has been spectroscopy. In mineral concentration plants valuable minerals are rendered hydrophobic by the action of certain surface active molecules, so called collectors. Other molecules, depressors, are used to prevent the collectors from acting also on the less desirable minerals. Even if many potent reagents are available the selectivity is not always satisfying. To design new, selective molecules an understanding of the fundamental reactions at the ZnS/water interface is essential. The acidic and alkaline sites of Zns have been identified by FI-IR spectroscopy. The dependence of stoichiometry and pH has been determined. Adsorption onto ZnS of one common collector, amyl xanthate, one potential collector, thionalide an one depressor has been investigated. The conditions for adsorption with regard to pH, concentration, stoichiometry and temperature have been determined. Adsorption mechanisms are proposed.